Although a Scrum Master is said to facilitate the team to produce the best results, workshop facilitation is sometimes a different matter.
A workshop facilitator must be independent of the topics being discussed and should not contribute facts or opinions to the conversation.
In most general product development workshops, if he/she has the skills, the Scrum Master may facilitate the workshop.
However, if the workshop is to discuss something like modifying the Scrum process, the Scrum Master does have important things to contribute and should not facilitate that workshop.